$CH_3COOH \xrightarrow{\Delta, P_2O_5} X$. Identify $X$.

Explain hydrogen bonding in carboxylic acids and its effect on their boiling points.

In the following reaction,$X$ and $Y$ respectively are:
$C_2H_5OH$ $\xrightarrow{KMnO_4 / H^+} X$ $\xrightarrow{C_2H_5OH / H_2SO_4, \Delta} CH_3COOC_2H_5$

Which of the following is the strongest carboxylic acid?

Identify the compounds $A$,$B$,and $C$ in the following reaction sequence:
$CH_3-Br$ $\xrightarrow{Mg, \text{Ether}} [A]$ $\xrightarrow[(ii) \text{Water}]{(i) CO_2} [B]$ $\xrightarrow{CH_3OH, H^+} [C]$

Which is the incorrect order of increasing acidic strength for the following?